• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.56-56
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• 2020

하도식생은 흐름과 유사의 이송에 영향을 주고, 하도의 지형변화를 일으키는데 중요한 역할을 하다. 하도 식생의 밀도가 증가하면, 하안의 안정성이 증가하고 하안침식이 감소하며, 사주의 형상과 거동에 영향을 준다. 또한 하천의 사행발달 및 하천의 지형변화에 영향을 준다. 식생의 성장과 밀도는 홍수 및 하상변동에 의하여 영향을 받으며, 이는 흐름 및 하천의 지형에 영향을 준다. 따라서 본 연구에서는 하도식생에 의한 사행하천의 발달과정을 2차원 수치모형을 적용하여 분석하였다. 하도식생의 생의 성장과 소멸과정을 고려하여 식생밀도를 고려하여 사행하천의 변화 과정을 분석하였다. 초기에 하안침식이 발생하고, 하폭이 증가하였다. 특히, 흐름이 집중되는 만곡부에서 하안침식이 증가하며, 하도의 사행도가 증가하였다(Fig.1(b)). 시간이 증가하면서 만곡부 내측에서 고정사주 내측에서 scroll bar가 발달하며, 만곡부 외측에서는 하안침식이 발생하고, 사행도가 증가하였다. 또한 식생의 침수시간이 감소하고 식생의 성장률은 증가하였다(Fig.1(c)). 식생의 밀도가 증가함에 따라 사행도는 증가하였다. 식생의 밀도가 증가함에 따라,

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.245.1-245.1
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• 2014

교차하는 전기장과 자기장으로 플라즈마를 방전하고, 이온 빔을 효과적으로 가속하는 원형 이온 빔 소스를 개발하였다. 방위각 방향으로 비대칭적인 중성 가스와 전자 빔의 공급으로 이온 빔 소스에서 불안정하고 불균일한 플라즈마가 방전되어, 이온 소스의 효율을 저하시킨다. 본 연구에서는 플라즈마 이미지를 이용하여 이온 소스 내부에서의 중성입자 밀도 분포를 측정하는 방법을 개발하였다. 자기장의 방향이 서로 다른 방전조건에서 얻어지는 한 쌍의 플라즈마 이미지로부터 티코노프 정형화 기법을 이용하여 방위각에 대한 중성입자의 밀도 분포를 재구성한다. 본 재구성 기법을 이용하여 얻어진 밀도 분포는 유체흐름 등가회로 모델을 바탕으로 한 수치해석을 이용하여 분석하였다. 중성입자 밀도의 공간분포는 인가 전압, 자기장의 세기 및 유량과 같은 방전조건의 변화에 크게 영향을 받지 않고, 가스 공급부의 내부 구조에 의해 결정되는 것을 확인하였다. 또한, 등가회로 모델을 이용하여 균일한 공간분포를 얻기 위한 공급부 설계를 수행하였다.

• Journal of Korean Society of Transportation
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• v.23 no.8 s.86
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• pp.53-66
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• 2005

This paper analyzes the effects of acceleration lane lengths on the traffic characteristics of merging areas. Two merging areas, Suwon IC and Singal JC, which have remarkably different acceleration lane length were selected as field study sites. Traffic data were collected through dividing each merging area into several subsections. Not only conventional flow, speed and density data but also a newly introduced MOE, density variation were used to analyzed the characteristics of merging area. Singal JC which has longer acceleration lane than Suwon IC showed more severe congestion, and the cause of the results was figured out.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.100-108
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• 1988

This research was performed to estimate the influence of relative light intensity, planting density, growth period on the growth of fresh and dry weight of the stem and branches, and root in the pretreatment transplanting bed. 1. The growth of fresh and dry weight of the stem and branches per seedling varied in the order of 63%>100%>37%>19% in relative light intensity, and increased with decrease of planting density, and grew highly during the period from May to June. The contribution rates to the growth of fresh and dry weight of the stem and branches were 49.4% and 39.6% in shading treatment, and 4.3% and 6.4% in planting density, and 34.2% in growth period respectively. Of the three factors, that is, shading, density and period, all of the interactions between two factors, and among the three factors in the growth of fresh and dry weight of stem and branches were significant. The growth of fresh and dry weight of root per seedling increased with light intensity and decreased with increase of density. The best growth of root, showed during the period from May to June in fresh weight, but during the period from July and August in dry weight of root. For the three factors, that is, shading, density and growth period, all the interactions between any two factors, and among the three factors in the growth of fresh and dry weight of root were significant.

• 한국도로학회:학술대회논문집
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• 2001.10a
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• pp.115-122
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• 2001

• Journal of Wetlands Research
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• v.11 no.1
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• pp.29-37
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• 2009

This study was conducted on the marsh of Paldang dam and Gyungan-cheon, Gyeonggi-do province. 6 species bred on the emergent plants and the nests of Common Coots Fulica atra, Common Moorhens Gallinula chloropus, Great Reed-Warblers Acrocephalus orientalis, Yellow Bitterns Ixobrychus eurhythmus, Little Grebes Podiceps ruficollis and Great Crested Grebes Podiceps cristatus were found. The main vegetations of the nests were Narrow Leaf Cattails Typha angustata, Reeds Phragmites communis, and Wild Rices Zizania latitolia. Particularly, Narrow Leaf Cattails were the most favorite plants for breeding birds. Few nests were found on the emergent plants covered with rubbish, or on high density. And no nests found on the inside shrubs. The mean density of nests on the marsh was 3.1 nests per ha and the nests were highest in Non-island as 17 nests per ha. The nest density on the area of Sonae-islands was higher than the area of Kyangdong-kyo bridge. This would be related on the bulk of narrow-leaf cattails and the quality of water.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.49-58
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• 2006

The purpose of this study is to develop transportation-sensitive land use densities in a metropolitan context. It analyses traffic impacts according to 20 different development density scenarios in the downtown Seoul, and estimates the density ceiling. The results identify that the transportation-wise sustainable density in the downtown can be extended up to the FAR level of 460% with an option of 2,000 won congestion charge levied on the downtown area. It also finds that the region-wide sustainability measured by congestion level can be improving as the level of congestion charge increases. Without the congestion charge, however, the density ceiling slides down to 430%. It is recommended that, in order to bring in higher density developments in the region, transportation demand management (TDM) measures are indispensible.

• Journal of Korea Water Resources Association
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• v.32 no.1
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• pp.83-94
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• 1999

In continental margins, turbid underflows which are not confined to a given channel, are free to spread laterally as well as longitudinally. Lateral spreading can reduce substantially the run out distance of flows along continental shelves and slopes. Laboratory experiments with a large tank, employing saline density currents as surrogates for fine-grained turbidity flow, coupled with dimensional analysis, have been used to develop a simple expression for lateral spreading rates of two-dimensional flows on sloping beds. characteristic length and time are determined by the flow discharge and buoyancy flux at the inlet. By knowing the initial width of the flow, the spreading law can be used to estimate the maximum width of the current at different times as well as the longitudinal spreading rate. Predictions for flows compare favorably against observations.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.427-428
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• 2014

화재발생 시 인명 안전을 위하여 초기의 화재감지가 매우 중요한 요인이다. 기존 연기감지기의 경우 일정한 조건만 맞으면 작동하기 때문에 비화재보의 우려가 높다. 특히 차량 매연도 연료가 연소되어 나오는 연기이므로 차량정체 시 트럭 등에서 발생하는 심한 매연에도 반응하여 오작동의 가능성이 높다. 이러한 기존 화재감지기의 문제점을 해결하기 위해 다양한 IR 레이저 기반 연기검출장치가 활용되고 있다. 하지만 IR 레이저 기반 연기검출장치는 100m 거리가 이격된 레이저 발광부와 수광부 구조에 따라 발광부 레이저광선의 각도변화에 따른 수광부 레이저 포인트 위치가 매우 민감하게 변화함에 따라 초기 레이저 포인트의 초점을 정확히 정합하고, 이후 보정하기 위한 고정밀 자동 초점 정합장치가 필요하다. 이에 본 논문에서는 레이저 투광부와 수광부를 분리하여 레이저 송신기, 수신기로 구성되는 고정밀 자동초점 정합장치를 설계하고자 한다.

• Journal of Korea Water Resources Association
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• v.50 no.1
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• pp.55-64
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• 2017

This study presents a numerical model for simulating turbidity currents using the ULTIMATE scheme. For this, the layer-averaged model is used. The model is applied to laboratory experiments, where the flume is composed of sloping and flat parts, and the characteristics of propagating turbidity currents are investigated. Due to the universal limiter of the ULTIMATE scheme, the frontal part of the turbidity currents at a sharp gradient without numerical oscillations is computed. Simulated turbidity currents propagate super-critically to the end of the flume, and internal hydraulic jumps occur at the break-in-slope after being affected by the downstream boundary. It is found that the hydraulic jumps are computed without numerical oscillations if Courant number is less than 1. In addition, factors that affect propagation velocity of turbidity currents is studied. The particle size less than $9{\mu}m$ does not affect propagation velocity but the buoyancy flux affects clearly. Finally, it is found that the numerical model computes the bed elevation change due to turbidity currents properly. Specifically, a discontinuity in the bed elevation, arisen from the hydraulic jumps and resulting difference in sediment entrainment, is observed.